scholarly journals Recurrent and Sporadic Listeria monocytogenes Contamination in Alheiras Represents Considerable Diversity, Including Virulence-Attenuated Isolates

2007 ◽  
Vol 73 (12) ◽  
pp. 3887-3895 ◽  
Author(s):  
M. T. S. Fel�cio ◽  
T. Hogg ◽  
P. Gibbs ◽  
P. Teixeira ◽  
M. Wiedmann
Keyword(s):  
Listeria Monocytogenes ◽  
Control Strategies ◽  
Tetracycline Resistance ◽  
The United States ◽  
Pulsed Field Gel Electrophoresis ◽  
Pathogenic Potential ◽  
Molecular Serotyping ◽  
Production And Distribution ◽  
Invasion Assays

ABSTRACT Microbiological characterization of alheiras, traditional smoked meat sausages produced in northern Portugal, had previously shown that more than 60% of the lots analyzed were contaminated with Listeria monocytogenes at levels higher than 100 CFU/g. In order to better understand L. monocytogenes contamination patterns in alheiras, we characterized 128 L. monocytogenes isolates from alheiras using a variety of subtyping techniques (i.e., molecular serotyping; arsenic, cadmium, and tetracycline resistance typing; and pulsed-field gel electrophoresis [PFGE]). Subtyping of isolates from products collected on two separate dates provided evidence for the persistence of specific L. monocytogenes PFGE types in the production and distribution chains of alheiras from four different processors. A subset of 21 isolates was further characterized using ribotyping and Caco-2 cell invasion assays to evaluate the pathogenic potential of L. monocytogenes present in alheiras. Caco-2 invasion assays revealed seven isolates with invasion efficiencies that were less than 20% of that of the control strain 10403S. All seven isolates had premature stop codons in inlA that represented three distinct mutations, which had previously been observed in isolates from the United States or France. Our findings indicate the need for a comprehensive approach to control L. monocytogenes in alheiras, including strategies to reduce persistence. The presence of considerable diversity in invasion phenotypes among L. monocytogenes strains present in alheiras, including the presence of subtypes likely to be virulence attenuated, may provide an opportunity to initially focus control strategies on the subtypes most likely to cause human disease.

Low Potential Virulence Associated with Mutations in the inlA and prfA Genes in Listeria monocytogenes Isolated from Raw Retail Poultry Meat

2013 ◽  
Vol 76 (1) ◽  
pp. 129-132 ◽  
Author(s):  
VICTORIA LÓPEZ ◽  
JAIME NAVAS ◽  
JOAQUÍN V. MARTÍNEZ-SUÁREZ
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Virulence Genes ◽  
Pulsed Field Gel Electrophoresis ◽  
Poultry Meat ◽  
Pathogenic Potential ◽  
Molecular Serotyping ◽  
Potential Source ◽  
Raw Foods ◽  
Over Time

Packaged raw foods can represent a potential source of Listeria monocytogenes contamination when opened at home, and listeriosis is associated with the consumption of undercooked raw foods. The aim of this study was to characterize a group of L. monocytogenes strains isolated from 56 packages of raw chicken meat from a single brand in order to determine the diversity of the strains that dominate in a particular food over time, as well as their pathogenic potential. Forty (71%) samples were found to be positive for L. monocytogenes, and three isolates per sample were subjected to PCR molecular serotyping. Subtyping of 45 isolates from different manufacturing dates (n = 40) or different molecular serotype within the same sample (n = 5) identified 11 different L. monocytogenes subtypes as defined by pulsed-field gel electrophoresis and sequencing of virulence genes actA and inlA. Two of the subtypes accounted for 51% of the isolates. About 40% of isolates (three subtypes) were found to potentially present attenuated virulence because of the presence of mutations in the prfA and inlA genes.

scholarly journals Prevalence and Genetic Characterization of Listeria monocytogenes in Retail Broiler Meat in Estonia

2006 ◽  
Vol 69 (2) ◽  
pp. 436-440 ◽  
Author(s):  
KRISTI PRAAKLE-AMIN ◽  
MARJA-LIISA HÄNNINEN ◽  
HANNU KORKEALA
Keyword(s):  
Genetic Diversity ◽  
Listeria Monocytogenes ◽  
Genetic Characterization ◽  
The United States ◽  
Pulsed Field Gel Electrophoresis ◽  
Broiler Meat ◽  
Pfge Typing ◽  
Foreign Origin ◽  
Serotype 1

The prevalence and genetic diversity of Listeria monocytogenes in raw broiler legs at the retail level in Estonia were studied. A total of 240 raw broiler legs (120 from Estonia and 120 of foreign origin, which had been imported to Estonia from Denmark, Finland, Hungary, Sweden, and the United States) from 12 retail stores in the two largest cities in Estonia (Tallinn and Tartu) were investigated from January to December 2002. Of these, 70% were positive for L. monocytogenes. The prevalence of L. monocytogenes in broiler legs of Estonian origin (88%) was significantly higher than in broiler legs of foreign origin (53%) (P < 0.001). Altogether, 169 (106 Estonian and 63 imported) L. monocytogenes isolates were characterized by pulsed-field gel electrophoresis (PFGE) typing after treatment with the restriction enzyme AscI. The isolates showed a wide genetic diversity, with 35 different PFGE types obtained. Of these, 11 PFGE types came only from isolates of broiler legs of Estonian origin, 4 of Danish origin, 2 of Finnish origin, and 4 of Hungarian origin. Fourteen PFGE types came from isolates of broiler legs that originated from various countries. The strains that shared the same PFGE types from isolates of Estonian origin were recovered from broiler legs that came from different stores over the course of several months. Seventy-one L. monocytogenes isolates, including all PFGE types, were serotyped, and three serotypes (1/2a, 1/2b, and 4b) were obtained. Serotype 1/2a accounted for 96% of the isolates.

Characterization of Listeria monocytogenes strains isolated from food and humans in Italy by pulsed-field gel electrophoresis

2002 ◽  
Vol 19 (1) ◽  
pp. 47-55 ◽  
Author(s):  
M Gianfranceschi ◽  
M Pourshaban ◽  
A Gattuso ◽  
C Wedell-Neergaard ◽  
P Aureli
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Pulsed Field

scholarly journals Listeria monocytogenes Isolates from Foods and Humans Form Distinct but Overlapping Populations

2004 ◽  
Vol 70 (10) ◽  
pp. 5833-5841 ◽  
Author(s):  
Michael J. Gray ◽  
Ruth N. Zadoks ◽  
Esther D. Fortes ◽  
Belgin Dogan ◽  
Steven Cai ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Plaque Assay ◽  
Virulence Gene ◽  
The United States ◽  
Polymorphism Analysis ◽  
Genetic Lineages ◽  
The Public ◽  
Cell Spread ◽  
Specific Food

ABSTRACT A total of 502 Listeria monocytogenes isolates from food and 492 from humans were subtyped by EcoRI ribotyping and PCR-restriction fragment length polymorphism analysis of the virulence gene hly. Isolates were further classified into genetic lineages based on subtyping results. Food isolates were obtained through a survey of selected ready-to-eat food products in Maryland and California in 2000 and 2001. Human isolates comprised 42 isolates from invasive listeriosis cases reported in Maryland and California during 2000 and 2001 as well as an additional 450 isolates from cases that had occurred throughout the United States, predominantly from 1997 to 2001. Assignment of isolates to lineages and to the majority of L. monocytogenes subtypes was significantly associated with the isolate source (food or human), although most subtypes and lineages included both human and food isolates. Some subtypes were also significantly associated with isolation from specific food types. Tissue culture plaque assay characterization of the 42 human isolates from Maryland and California and of 91 representative food isolates revealed significantly higher average infectivity and cell-to-cell spread for the human isolates, further supporting the hypothesis that food and human isolates form distinct populations. Combined analysis of subtype and cytopathogenicity data showed that strains classified into specific ribotypes previously linked to multiple human listeriosis outbreaks, as well as those classified into lineage I, are more common among human cases and generate larger plaques than other subtypes, suggesting that these subtypes may represent particularly virulent clonal groups. These data will provide a framework for prediction of the public health risk associated with specific L. monocytogenes subtypes.

Pulsed-field gel electrophoresis applied for comparing Listeria monocytogenes strains involved in outbreaks

1993 ◽  
Vol 39 (4) ◽  
pp. 395-401 ◽  
Author(s):  
C. Buchrieser ◽  
R. Brosch ◽  
B. Catimel ◽  
J. Rocourt
Keyword(s):  
United States ◽  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
The United States ◽  
Pulsed Field Gel Electrophoresis ◽  
Chromosomal Dna ◽  
Restriction Patterns ◽  
Pulsed Field ◽  
Dna Restriction Fragments ◽  
Dna Restriction

Recent food-borne outbreaks of human listeriosis as well as numerous sporadic cases have been mainly caused by Listeria monocytogenes serovar 4b strains. Thus, it was of interest to find out whether a certain clone or a certain few clones were responsible for these cases and especially for outbreaks., We used pulsed-field gel electrophoresis of large chromosomal DNA restriction fragments generated by ApaI, SmaI, or NotI to analyse 75 L. monocytogenes strains isolated during six major and eight smaller recent listeriosis outbreaks. These strains could be divided into 20 different genomic varieties. Thirteen of 14 strains isolated during major epidemics in Switzerland (1983–1987), the United States (California, 1985) and Denmark (1985–1987) demonstrated indistinguishable DNA restriction patterns. In contrast, strains responsible for the outbreaks in Canada (Nova Scotia, 1981), the United States (Massachusetts, 1983), France (Anjou, 1975–1976), New Zealand (1969), and Austria (1986) and some smaller outbreaks in France (1987, 1988, 1989) were each characterized by particular combinations of DNA restriction patterns. Seventy-seven percent of the tested strains could be classified into the previously described ApaI group A (Brosch et al. 1991), demonstrating a very close genomic relatedness. Because 49% of the epidemic strains selected for this study belonged to phagovar 2389/2425/3274/2671/47/108/340 or 2389/47/108/340, fifty-six additional strains of these phagovars, isolated from various origins, were also typed to determine whether differences in DNA restriction profiles between epidemic and randomly selected strains of the same phagovars could be pointed out. Variations in DNA patterns appeared more frequently within randomly selected strains than within epidemic strains.Key words: Listeria monocytogenes, listeriosis, typing, pulsed-field gel electrophoresis, epidemic.

Distribution of Epidemic Clonal Genetic Markers among Listeria monocytogenes 4b Isolates

2007 ◽  
Vol 70 (3) ◽  
pp. 574-581 ◽  
Author(s):  
GIOVANNA FRANCIOSA ◽  
CONCETTA SCALFARO ◽  
ANTONELLA MAUGLIANI ◽  
FRANCESCA FLORIDI ◽  
ANTONIETTA GATTUSO ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Genetic Markers ◽  
Pulsed Field Gel Electrophoresis ◽  
Genomic Diversity ◽  
Clinical Isolates ◽  
Specific Marker ◽  
Environmental Isolates ◽  
Environmental Persistence ◽  
Pathogenic Potential ◽  
Serotype 4B

Recent genome sequencing of isolates of Listeria monocytogenes serotype 4b implicated in some major outbreaks of foodborne listeriosis has revealed unique genetic markers in these isolates. The isolates were grouped into two distinct epidemic clones, ECI and ECII. In the present study, selected ECI- and ECII-specific genetic markers were detected in 16 and 15 of 89 L. monocytogenes 4b isolates, respectively. The ECI markers were found in 6 of 34 clinical isolates, 9 of 50 food isolates, and 1 of 5 environmental isolates, and the ECII markers were detected in 7 of 34 clinical isolates, 7 of 50 food isolates, and 1 of 5 environmental isolates. Hence, of the isolates with the epidemic clonal genetic markers, 38% (13 of 34) were of clinical origin, 32% (16 of 50) were of food origin, and 40% (2 of 5) were of environmental origin. The predominance of the epidemic clonal markers among the clinical and environmental isolates supports the hypothesis that these markers are correlated with the pathogenic potential of strains and with their environmental persistence. Several isolates had only one epidemic clonal marker, either the ECI-specific marker 133 or the ECII-specific marker 4bSF18. Pulsed-field gel electrophoresis analysis revealed higher genomic diversity among the strains with ECII-like characteristics than among those strains carrying the ECI-specific genetic markers.

scholarly journals Revelation by Single-Nucleotide Polymorphism Genotyping That Mutations Leading to a Premature Stop Codon in inlA Are Common among Listeria monocytogenes Isolates from Ready-To-Eat Foods but Not Human Listeriosis Cases

2010 ◽  
Vol 76 (9) ◽  
pp. 2783-2790 ◽  
Author(s):  
A. Van Stelten ◽  
J. M. Simpson ◽  
T. J. Ward ◽  
K. K. Nightingale
Keyword(s):  
United States ◽  
Single Nucleotide Polymorphism ◽  
Listeria Monocytogenes ◽  
Stop Codon ◽  
Human Health Risk ◽  
Premature Stop Codon ◽  
The United States ◽  
Nucleotide Polymorphism ◽  
Pathogenic Potential ◽  
Single Nucleotide

ABSTRACT Listeria monocytogenes utilizes internalin A (InlA; encoded by inlA) to cross the intestinal barrier to establish a systemic infection. Multiple naturally occurring mutations leading to a premature stop codon (PMSC) in inlA have been reported worldwide, and these mutations are causally associated with attenuated virulence. Five inlA PMSC mutations recently discovered among isolates from France and the United States were included as additional markers in our previously described inlA single-nucleotide polymorphism (SNP) genotyping assay. This assay was used to screen >1,000 L. monocytogenes isolates from ready-to-eat (RTE) foods (n = 502) and human listeriosis cases (n = 507) for 18 inlA PMSC mutations. A significantly (P < 0.0001) greater proportion of RTE food isolates (45.0%) carried a PMSC mutation in inlA compared to human clinical isolates (5.1%). The proportion of L. monocytogenes with or without PMSC mutations in inlA was similar among isolates from different RTE food categories except for deli meats, which included a marginally higher proportion (P = 0.12) of isolates carrying a PMSC in inlA. We also analyzed the distribution of epidemic clone (EC) strains, which have been linked to the majority of listeriosis outbreaks worldwide and are overrepresented among sporadic cases in the United States. We observed a significant (P < 0.05) overrepresentation of EC strains in deli and seafood salads and a significant (P < 0.05) underrepresentation of EC strains in smoked seafood. These results provide important data to predict the human health risk of exposure to L. monocytogenes strains that differ in pathogenic potential through consumption of contaminated RTE foods.

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